International aid groups are preparing to return to southern Somalia nearly two years after threats by a radical Islamic group forced them out, but a devastating and spreading famine has forced the the agencies to do whatever is necessary to save lives.

The agencies are also acting in the face of U.S. concern that the aid could end up bolstering the al-Qaeda affiliated terror group Al-Shabaab.

Parts of southern Somalia have now been officially declared a famine, the first of the 21st century according to the United Nations. Nearly 3 million Somalis are affected and aid organizations are grappling with how to reach the most destitute areas, which are currently under the control of the militant Islamic group Shabaab.

The humanitarian "emergency" became a "famine" after the U.N. determined more than 30 percent of children in the areas were suffering from acute malnutrition, and two adults or four children out of a group of 10,000 people were dying of hunger each day.

"If we don't act now, famine will spread to all eight regions of southern Somalia within two months, due to poor harvests and infectious disease outbreaks," said Mark Bowden, the humanitarian coordinator for Somalia. "We still do not have all the resources for food, clean water, shelter and health services to save the lives of hundreds of thousands of Somalis in desperate need."

International humanitarian organizations have not operated in the area for nearly two years. Most pulled out in early 2010 because of insecurity and demands by Al -Shabaab, such as banning women aid workers and charging a "tax" on all assistance. The tax was particularly problematic because giving any money or goods to the group would be violating U.S. anti-terrorism funding laws.

Al Shabaab has been declared a terrorist organization by the United States, which historically has been the largest funder of food aid to Somalia.

But now, with hundreds of thousands Somalis starving to death as they take the treacherous journey from their drought-stricken homes to overcrowded refugee camps in neighboring Kenya and Ethiopia, humanitarian agencies say there is no choice but to do whatever is necessary to save lives, even if that means dealing with Shabaab.

"While U.N. humanitarian agencies have welcomed the recent statement by Al Shabaab requesting international assistance in southern Somalia, the inability of food agencies to work in the region since early 2010 has prevented the U.N. from reaching the very hungry -- especially children -- and has contributed to the current crisis," said Bowden.

Some organizations have been openly critical of the U.S., saying that it's position is partially responsible for the current disaster.

Bowden told reporters today in Nairobi, Kenya, that the United States' sanctions against al Shabaab "complicates efforts through increased levels of suspicion and motivation so it may lead to access problems in parts. We hope there is an understanding that this is a humanitarian imperative to get assistance in."

Famine Has Aid Agencies and Islamic Militants Working Together in Somalia

The United States maintains that the problem is not with U.S. policy, but with al Shabaab. The group is known for its brutal leadership including stoning a 13-year-old girl to death after she was raped, dismembering alleged thieves, and banning movies, cell phone ring tones and even bras.

"U.S. sanctions are not the issue or the problem," says Johnnie Carson, the Assistant Secretary of African Affairs at the State Department.

Secretary of State Hillary Clinton announced in a statement that the United States will provide an additional $28 million in emergency aid money to the Somalis in dire need.

Two years ago Shabaab banned all foreign aid agencies, accusing them of having an anti-Muslim agenda. Since the crisis Shabaab leadership announced it was lifting the ban and asked for help, setting up "drought committees" to vet humanitarian agencies to make sure they had no "hidden agenda."

The U.N. says it's using local sources on the ground to talk with these committees. UNICEF has already delivered aid in some Shabaab-controlled areas and it said has been distributed unfettered.

The World Food Program, which is the largest distributer of food aid in the world, said today some of the options for delivering aid include airlifting high energy biscuits and nutritious food supplements into some of the worst-affected and least secure areas. The food would be then be distributed to the hungry by the few local humanitarian groups working in the areas.

"The challenge now is how to put back in place a sustainable delivery system where we can be sure it reaches the right people, where we have security on the ground for our staff," Stephanie Savariaud, the WFP Africa spokesperson told ABC News. "I'ts not just about dropping the food somewhere. It's about securing the area it's going to be in. And about putting into place a system of distribution to make sure the food goes to the right people."

Savariaud acknowledges that trying to intervene in a lawless country that hasn't had a functioning government in more than 20 years is a daunting task, but with millions of lives at stake, not intervening isn't an option.

"Humanitarian principles have been challenged," she said. "But we still have to help."